The impact of grazing intensity on the allelopathic effect of Artemisia frigida in a temperate grassland in northern China

Aim. To determine the response of the populations of Erysipelothrix rhusiopathiae and Leptospira interrogans pathogenic microorganisms to the impact of broadleaf cattail (Thypha latifolia) root diffusates. Methods. Aqueous solutions of T. latifolia root diffusates were sterilized by vacuum fi ltration through the fi lters with 0.2-micron pore diameter. The experimental samples contained cattail secretions, sterile water, and cultures of E. rhusiopathiae or L. interrogans. The same amount of sterile water, as in the experimental samples, was used for the purpose of control, and the same quantity of microbial cultures was added in it. After exposure, the density of cells in the experimental and control samples was determined. Results. Root diffusates of T. latifolia caused an increase in cell density in the populations of E. rhusiopathiae throughout the whole range of the studied dilutions (1:10–1:10000). In the populations of the 6 studied serological variants of L. interrogans spirochetes (pomona, grippotyphosa, copenhageni, kabura, tarassovi, canicola), the action of broadleaf cattail root diffusates caused the decrease in cell density. A stimulatory effect was marked in the experimental samples of the pollonica serological variant of leptospira. Conclusions. The populations of E. rhusiopathiae and L. interrogans pathogenic microorganisms respond to the allelopathic effect of Thypha latifolia by changing the cell density. The obtained results provide the background to assume that broadleaf cattail thickets create favorable conditions for the existence of E. rhusiopathiae pathogen bacteria. The reduced cell density of L. interrogans in the experimental samples compared to the control samples observed under the infl uence of T. latifolia root diffusates suggests that reservoirs with broadleaf cattail thickets are marked by the unfavorable conditions for the existence of pathogenic leptospira (except L. pollonica).

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Effect of the Assimilation Frequency of Radar Reflectivity on Rain Storm Prediction by Using WRF-3DVAR

Remote Sensing ◽

10.3390/rs13112103 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2103

Author(s):

Yuchen Liu ◽

Jia Liu ◽

Chuanzhe Li ◽

Fuliang Yu ◽

Wei Wang

Keyword(s):

Data Assimilation ◽

Northern China ◽

Horizontal Resolution ◽

Radar Reflectivity ◽

Small Scale ◽

Time Interval ◽

Outer Domain ◽

Storm Prediction ◽

The Impact ◽

Assimilation Time

An attempt was made to evaluate the impact of assimilating Doppler Weather Radar (DWR) reflectivity together with Global Telecommunication System (GTS) data in the three-dimensional variational data assimilation (3DVAR) system of the Weather Research Forecast (WRF) model on rain storm prediction in Daqinghe basin of northern China. The aim of this study was to explore the potential effects of data assimilation frequency and to evaluate the outputs from different domain resolutions in improving the meso-scale NWP rainfall products. In this study, four numerical experiments (no assimilation, 1 and 6 h assimilation time interval with DWR and GTS at 1 km horizontal resolution, 6 h assimilation time interval with radar reflectivity, and GTS data at 3 km horizontal resolution) are carried out to evaluate the impact of data assimilation on prediction of convective rain storms. The results show that the assimilation of radar reflectivity and GTS data collectively enhanced the performance of the WRF-3DVAR system over the Beijing-Tianjin-Hebei region of northern China. It is indicated by the experimental results that the rapid update assimilation has a positive impact on the prediction of the location, tendency, and development of rain storms associated with the study area. In order to explore the influence of data assimilation in the outer domain on the output of the inner domain, the rainfall outputs of 3 and 1 km resolution are compared. The results show that the data assimilation in the outer domain has a positive effect on the output of the inner domain. Since the 3DVAR system is able to analyze certain small-scale and convective-scale features through the incorporation of radar observations, hourly assimilation time interval does not always significantly improve precipitation forecasts because of the inaccurate radar reflectivity observations. Therefore, before data assimilation, the validity of assimilation data should be judged as far as possible in advance, which can not only improve the prediction accuracy, but also improve the assimilation efficiency.

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The Impacts of Groundwater Chemistry on Wetland Vegetation Distribution in the Northern Qinghai–Tibet Plateau

Sustainability ◽

10.3390/su11185022 ◽

2019 ◽

Vol 11 (18) ◽

pp. 5022 ◽

Cited By ~ 3

Author(s):

Junju Zhou ◽

Juan Xiang ◽

Lanying Wang ◽

Guoshuang Zhong ◽

Guofeng Zhu ◽

...

Keyword(s):

Multiple Scales ◽

Groundwater Chemistry ◽

Ion Concentration ◽

Tibet Plateau ◽

Distribution Data ◽

Vegetation Distribution ◽

Chemical Parameters ◽

Weakly Alkaline ◽

Artemisia Frigida ◽

The Impact

Groundwater chemistry has an important impact on the vegetation distribution in inland areas. An in-depth understanding of the impact of groundwater chemistry on vegetation can help in developing an effective management strategy to protect the inland ecosystem. The aim of this study was to identify the influence of groundwater chemicals on species diversity and the distribution characteristics of wetland plants at multiple scales based on the groundwater chemical data from 15 sampling points and the distribution data of 13 plants in the Sugan Lake Wetland in 2016. The results show that the groundwater of the Sugan Lake Wetland is weakly alkaline, with high salinity and hardness; the water chemical type is Na-SO4-Cl; the concentration of the major water chemical parameters is significantly different and is the highest in the northwest, followed by the southwest, and is the lowest in the east; with an increase in the groundwater depth, the concentration of major water chemical parameters first showed an increasing trend followed by a decreasing trend; Artemisia frigida Willd, Poa annua L. and Triglochin maritimum L. were adapted to the environment with a higher ion concentration of the groundwater, and their salt resistance was the strongest; Blysmus sinocompressus and Polygonum are more adapted to the environment with lower salinity and hardness of groundwater; Thermopsis lanceolata has stronger adaptability to the ion concentration, salinity, and hardness of groundwater; other plants are adapted to environments where the ion concentration, salinity, and hardness of the groundwater are moderate.

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Characterization of pasture biophysical properties and the impact of grazing intensity using remotely sensed data

Remote Sensing of Environment ◽

10.1016/j.rse.2007.01.013 ◽

2007 ◽

Vol 109 (3) ◽

pp. 314-327 ◽

Cited By ~ 82

Author(s):

Izaya Numata ◽

Dar A. Roberts ◽

Oliver A. Chadwick ◽

Josh Schimel ◽

Fernando R. Sampaio ◽

...

Keyword(s):

Grazing Intensity ◽

Remotely Sensed ◽

Biophysical Properties ◽

Remotely Sensed Data ◽

The Impact

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Impact of grazing intensity on seasonal variations in soil organic carbon and soil CO 2 efflux in two semiarid grasslands in southern Botswana

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2012.0102 ◽

2012 ◽

Vol 367 (1606) ◽

pp. 3076-3086 ◽

Cited By ~ 53

Author(s):

Andrew D. Thomas

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Seasonal Variations ◽

Field Experiments ◽

Grazing Intensity ◽

C Sequestration ◽

Ecosystem Functions ◽

Semiarid Environments ◽

The Impact ◽

And Storage

Biological soil crusts (BSCs) are an important source of organic carbon, and affect a range of ecosystem functions in arid and semiarid environments. Yet the impact of grazing disturbance on crust properties and soil CO 2 efflux remain poorly studied, particularly in African ecosystems. The effects of burial under wind-blown sand, disaggregation and removal of BSCs on seasonal variations in soil CO 2 efflux, soil organic carbon, chlorophyll a and scytonemin were investigated at two sites in the Kalahari of southern Botswana. Field experiments were employed to isolate CO 2 efflux originating from BSCs in order to estimate the C exchange within the crust. Organic carbon was not evenly distributed through the soil profile but concentrated in the BSC. Soil CO 2 efflux was higher in Kalahari Sand than in calcrete soils, but rates varied significantly with seasonal changes in moisture and temperature. BSCs at both sites were a small net sink of C to the soil. Soil CO 2 efflux was significantly higher in sand soils where the BSC was removed, and on calcrete where the BSC was buried under sand. The BSC removal and burial under sand also significantly reduced chlorophyll a , organic carbon and scytonemin . Disaggregation of the soil crust, however, led to increases in chlorophyll a and organic carbon. The data confirm the importance of BSCs for C cycling in drylands and indicate intensive grazing, which destroys BSCs through trampling and burial, will adversely affect C sequestration and storage. Managed grazing, where soil surfaces are only lightly disturbed, would help maintain a positive carbon balance in African drylands.

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Elevated CO2 Concentrations and Water Stress Affect the Ability of Italian Ryegrass to Remediate Herbicides and Enhance its Allelopathic Effect

Planta Daninha ◽

10.1590/s0100-83582019370100073 ◽

2019 ◽

Vol 37 ◽

Author(s):

L.P. SILVEIRA ◽

A.R. FEIJÓ ◽

C. BENETTI ◽

J.P. REFATTI ◽

M.V. FIPKE ◽

...

Keyword(s):

Water Stress ◽

Elevated Co2 ◽

Co2 Concentration ◽

Italian Ryegrass ◽

Allelopathic Effect ◽

Irrigated Rice ◽

Allelopathic Potential ◽

Co2 Concentrations ◽

Temporal Persistence ◽

The Impact

ABSTRACT: The long temporal persistence of select herbicides negatively impacts crops sown in succession to irrigated rice. One way to reduce these compounds in the soil over time is through phytoremediation. However, elevated CO2 concentrations may interfere with the phytoremediation process. Another consequence of climate change is the production of allelopathic compounds by forage species used as remedial agents. This study aimed to evaluate the impact of elevated CO2 concentration and drought stress on the remediation of soil samples contaminated with imazapyr + imazapic herbicides by Italian ryegrass and any subsequential affect on the allelopathic effect of this species. We report that the increasing CO2 decreased the phytoremediation potential of ryegrass. Water stress combined with a CO2 concentration of 700 µmol mol-1 caused increased allelopathy. Overall, these are the first data to indicate a significant effect of higher CO2 levels with respect to both phytoremediation efficacy and allelopathic potential of the plant species used in phytoremediation.

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The Impact of Air Pollution (PM2.5) on Atherogenesis in Modernizing Southern versus Northern China

Atmosphere ◽

10.3390/atmos12121552 ◽

2021 ◽

Vol 12 (12) ◽

pp. 1552

Author(s):

Kamsang Woo ◽

Changqing Lin ◽

Yuehui Yin ◽

Dongshuang Guo ◽

Ping Chook ◽

...

Keyword(s):

Risk Factors ◽

Air Pollution ◽

Northern China ◽

Age And Gender ◽

Carotid Imt ◽

Southern Chinese ◽

Northern Chinese ◽

Traditional Risk Factors ◽

And Gender ◽

The Impact

To evaluate the impact of PM2.5 air pollution on atherogenic processes in modernizing Southern versus Northern China, we studied 1323 asymptomatic Chinese in Southern and Northern China in 1996–2007. PM2.5 exposure and metabolic syndrome (MS) were noted. Brachial flow-mediated dilation (endothelial function FMD) and carotid intima-media thickness (IMT) were measured by ultrasound. Although age and gender were similar, PM2.5 was higher in Northern China than in Southern China. The Northern Chinese were characterized by lower lipids, folate and vitamin B12, but higher age, blood pressures, MS and homocysteine (HC) (p = 0.0015). Brachial FMD was significantly lower and carotid IMT was significantly greater (0.68±0.13) in Northern Chinese, compared with FMD and IMT (0.57 ± 0.13, p < 0.0001) in Southern Chinese. On multivariate regression, for the overall cohort, carotid IMT was significantly related to PM2.5, independent of location and traditional risk factors (Model R2 = 0.352, F = 27.1, p < 0.0001), while FMD was inversely related to gender, age, and northern location, but not to PM2.5. In Southern Chinese, brachial FMD was inversely correlated to PM2.5, independent of age, whereas carotid IMT was significantly related to PM2.5, independent of age and gender. In Northern Chinese, brachial FMD was inversely related to gender only, but not to PM2.5, while carotid IMT was related to traditional risk factors. Despite a higher PM2.5 pollution in Northern China, PM2.5 pollution was more significantly associated with atherogenic surrogates in Southern compared to Northern Chinese. This has potential implications for atherosclerosis prevention.

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Regional characteristics of spring Asian dust and its impact on aerosol chemistry over northern China

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-6-12825-2006 ◽

2006 ◽

Vol 6 (6) ◽

pp. 12825-12864 ◽

Cited By ~ 6

Author(s):

Y. L. Sun ◽

G. S. Zhuang ◽

Z. F. Wang ◽

Y. Wang ◽

W. J. Zhang ◽

...

Keyword(s):

Dust Storm ◽

Fine Particles ◽

Coastal Region ◽

Northern China ◽

Asian Dust ◽

Aerosol Chemistry ◽

Transport Pathway ◽

Regional Characteristics ◽

Source Regions ◽

The Impact

Abstract. TSP and PM2.5 aerosol samples were synchronously collected at six sites along the transport pathway of dust storm from desert regions to coastal areas in the spring of 2004. The aerosol concentration and composition were measured to investigate the regional characteristics of spring Asian dust and its impact on aerosol chemistry over northern China. Based on the daily PM10 concentrations in 13 cities, the northern China could be divided into five regions, i.e., Northern Dust Region, Northeastern Dust Region, Western Dust Region, Inland Passing Region, and Coastal Region. Northern Dust Region was characterized by high content of Ca and Northeastern Dust Region was characterized by low one instead. Northeastern Dust Region was a relatively clean area with the lowest concentrations of pollutants and secondary ions among all sites. Inland Passing Region and Coastal Region showed high concentrations of pollutants, of which As and Pb in Inland Passing Region, and Na+, SO42− and NO3− in Coastal Region were the highest, respectively. The impact of dust on air quality was the greatest in the cities near source regions, and this impact decreased in the order of Yulin/Duolun > Beijing > Qingdao/Shanghai as the increase of transport distance. The spring Asian dust was inclined to affect the chemical components in coarse particles near source regions and those in fine particles in the cities far from source regions. Dust storm could mix significant quantities of pollutants on the pathway and carry them to the downwind cities or dilute the pollutants in the cities over northern China. Each dust episode corresponded to a low ratio of NO3−/SO42− with the lowest value appearing after the peak of dust storm. Asian dust played an important role in buffering and neutralizing the acidity of atmosphere in the cities over northern China, which could lead to the pH in the aerosols increase ~1 in spring.

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Relative impact of insolation and Warm Pool surface temperature on the East Asia Summer Monsoon during the MIS-13 interglacial

Climate of the Past Discussions ◽

10.5194/cpd-10-1025-2014 ◽

2014 ◽

Vol 10 (2) ◽

pp. 1025-1051 ◽

Cited By ~ 3

Author(s):

Q. Z. Yin ◽

U. K. Singh ◽

A. Berger ◽

Z. T. Guo ◽

M. Crucifix

Keyword(s):

Surface Temperature ◽

Summer Monsoon ◽

Climate Modeling ◽

Southern China ◽

Asian Summer Monsoon ◽

Summer Precipitation ◽

Northern China ◽

Warm Pool ◽

Pool Surface ◽

The Impact

Abstract. During Marine Isotope Stage (MIS) 13, an interglacial about 500 000 years ago, the East Asian summer monsoon (EASM) was suggested exceptionally strong by different proxies in China. However, MIS-13 is a weak interglacial in marine oxygen isotope records and has relatively low CO2 and CH4 concentrations compared to other interglacials of the last 800 000 years. In the mean time, the sea surface temperature (SST) reconstructions show that the Western Pacific Warm Pool was relatively warm during MIS-13. Based on climate modeling experiments, this study aims at investigating whether this Warm Pool warming could explain the exceptionally strong EASM occurring during the relatively cool interglacial MIS-13. The individual contributions of insolation and of the Warm Pool SST as well as their synergism are quantified through experiments with the Hadley Centre atmosphere model, HadAM3 and using the factor separation technique. The SST over the Warm Pool region has been increased based on geological reconstructions. Our results show that the pure impact of a strong summer insolation contributes to strengthen significantly the summer precipitation in northern China but only little in southern China. The pure impact of enhanced Warm Pool SST reduces, slightly, the summer precipitation in both northern and southern China. However, the synergism between insolation and enhanced Warm Pool SST contributes to a large increase of summer precipitation in southern China but to a decrease in northern China. Therefore, the ultimate role of enhanced Warm Pool SST reinforces the impact of insolation in southern China but reduces its impact in northern China. We conclude that enhanced SST over the Warm Pool region does help to explain the strong MIS-13 EASM precipitation in southern China as recorded in proxy data, but other explanation is needed for explaining the exceptionally strong EASM in northern China.

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